Three dimensional structures are widely used as constitutional elements for structured coated abrasive materials, retro-reflective materials, Fresnel lenses, mechanical fasteners, and the like. Three dimensional structures having fine cube-corners, trigonals, pyramids, stripes sequentially formed on a plane surface, are the examples thereof. Industrially, such structures are formed by casting a resin into a mold with a reversed shape of a three dimensional structure to replicate it.
Japanese Patent Kohyo Publication No. H8-505572, Japanese Patent Kohyo Publication No. H9-502665 and Japanese Patent Kokai Publication No. 2003-236434 and the like describe methods and devices for continuously replicating a three dimensional structure by using a film-form production tool with a reversed shape of the structure which is an object to be replicated, on a surface. According to these methods, basically, a composition comprising a solidifiable resin is coated on a reversed shape of structure on a film-form production tool while it is being sent, a substrate is laminated thereon, the composition is solidified, and then the film-form production tool is removed from the cured resin.
The conventional methods for replicating structure are effective when compositions, objects to be molded, have a relatively low viscosity. When a high viscosity resin or composition is simply coated on a surface of a shape on a film-form production tool, however, it can be difficult for the resin or composition to penetrate into the inside of the shape, and moreover, air inclusion occurs, whereby it is hard to replicate the structure accurately.
On the other hand, decompression die coaters have hitherto been known. For example, Japanese Patent Kokai Publication No. 2003-236434 describes that in order to prevent coating unevenness, a coating film is formed on a substrate by using decompression die coater part. FIG. 1 of the publication 3 shows an embodiment wherein a coating film 14b is formed on a web 12 by using a slot die 13 with an discharge outlet 16a for a coating liquid 14. FIG. 1 does not clearly depict, but a blank space under the slot die 13 shows a decompression chamber.
According to this coating embodiment, the web 12, which is an article to be coated, is wound around a backup roll 11. This structure does not allow the web 12 to move toward the backup roll 11, thereby necessarily forming a space between the surface to be coated of the web 12 and the discharge outlet, by the thickness of the coating film. In other words, the surface to be coated of the web does not contact to a surface 18a of the discharge outlet of the slot die 13. Consequently, the conventional decompression die coater part must have such structure that coating liquid flows back toward the decompression chamber.
As a result, the conventional decompression die coater part cannot sufficiently enhance decompression degree of the decompression chamber, and it can be difficult to effectively impregnate high viscosity resin compositions into the inside of structure in a production tooling, even if they are used as coating means.